This invention relates generally to apparatus for drawing the ends of endless conveyor belts together for interconnection and more particularly to full width belt clamps for highly tensioning conveyor belts.
Fabric endless conveyor belts are widely used in plywood veneer mills and many other manufacturing applications. The belts operate at high speed under high tension and are often positioned in raceways. The belts can range from a few feet to dozens of feet in length. They are typically 3/16" to 1/4" thick and can be from a few inches to over 2' wide. Installation, replacement or repair of such belts requires drawing their ends together under tension for fastening. A variety of devices have been proposed for bringing together the ends of a broken endless conveyor belt to facilitate joining the ends. An example of such a device is shown in British Pat. No. 1,154,373 to Cook, et al.
One of the principal difficulties in the operation of such devices is securely connecting the pulling device to the ends of the belt. Soviet Union Patent No. 630,136 to Fedorov, et al. discloses a clamping device which clamps the margins of the belt. Devices such provide a similar function are known in the United States. A principal drawback of such clamping devices is that they do not clamp the entire width of the belt and thus apply most of the tension along the margins of the belt. As tension is applied, the centerline of the belt is not stretched as much as the margins, making it difficult to secure the ends together. Moreover, such clamping devices are subject to slippage. This clamping device is also inconvenient to use in raceways.
The aforementioned Cook, et al. patent uses a clamping device having a pair of eccentrically mounted parallel rollers, between which a length of conveyor belting is gripped. Although this clamping device spans the entire width of the belting, it slips under high tension. Also, because it is connected to the haulage device by means of two cables extending between the ends of both rollers, it cannot be conveniently used on short belts. Furthermore, the eccentric rollers and cable are difficult to fit into the raceways and to remove once the belt ends are connected together.
A third type of belt clamp is also known which utilizes a channel member which fits under the belt, the belt lying lengthwise in the channel. A rod extends across the belt between the sides of the channel member, which are slotted at an angle so as to force the rod downwardly in a camming action to clamp the belt against the base of the channel member as the clamp is pulled lengthwise of the belt. This clamp is also insecure when substantial tension is applied to the belt. It is also quite difficult both to use in a raceway and to remove from the belt once its ends are connected.
Another problem with the last-mentioned and the Fedorov, et al. clamping devices is that they are not reversible. The operating environment of conveyor belts often makes it difficult to conveniently fit a clamping device into a raceway in one direction whereas it might be much easier to do so in the opposite direction.
Accordingly, a need remains for a better form of belt clamp for use in connecting the ends of conveyor belts than has been previously known.